1. Field of the Invention
This invention relates in general to a device and method for applying precise irrigation, aspiration, medication, ultrasonic power and dwell time to biotissue for surgery and treatment and in particular to an improvement on and in addition to the device disclosed in our U.S. Pat. No. 3,990,452 which issued on Nov. 9, 1976.
2. Description of the Prior Art
Substantial experience during operations in medical operating rooms using the ultrasonic equipment shown in our U.S. Pat. No. 3,990,452 which issued on Nov. 9, 1976 has disclosed that the needs of surgeons for providing proper operating room care to patients is far more complex and difficult than was a first realized by those supplying aspirating, irrigating and ultrasonic equipment. For example, prior art devices are on the market which includes complex aspirators and irrigators for removing fluids from body cavities such as the eye, lungs, veins, kidneys and other organs; yet, very few physical--as opposed to physiological--in situ, measurements have been made in these cavities such as the pressures and flow rates therein, and litte if any effort has been made to provide precise flow and pressure control when working in such body cavities.
This some situation exists for infusing medicine or treatment fluids to bathe (lavage) or flood tissue on a controlled basis at the invasion site as is required by the attendant doctors.
When ultrasound is additionally used there has been concern about the exposure of the tissue to the radiation and occasionally to its heating effect, yet few if any instruments in use today have been able to measure the true power in watts per unit of time, or in other words, the time rate of doing work applied to the tissue. The reason for this is not because this data is not necessary and required but due to the fact that the instrumentation has not been available heretofore to obtain or control this unique form of energy.
Another discovery was that the same equipment used for irrigation, aspiration and applying measured ultrasonic power to biological tissues frequently must also apply medication such as drugs or treatment fluids, for example, to the cavity or tissue being invaded in a manner similar to the heart-lung machine wherein the medicines are supplied to the machine rather than directly to the patient.
Our study has illustrated that a total consideration of the problem requires analysis of at least the following areas:
a. Irrigation
b. Aspiration
c. Medication
d. Power Control
e. Duration Control
f. Supplementary Devices
For simplicity, it is assumed that the ultrasonic medical device described in our U.S. Pat. No. 3,990,452 will be used in the procedures described.
Definitions are where possible taken from Stedman's Medical Dictionary, 22 nd Edition.
A. Irrigation--(The washing out of a cavity or wound surface with a stream of fluid.)
The present art discloses bottles, flasks, retorts, tanks, etc., which are elevated or hanging, pressurized and so forth. All of these have one common feature for medical work and that is that they must contain sterile treatment or lavaging fluid so as to make it available to the attendants as needed. A great deal of ingenuity has gone into devising irrigation systems, some being very complex such as the closed cycle, blood circulatory system of the heart/lung machine; while others are as simple as a hanging I.V. bottle which has been used at least since 1902.
Some systems which use the hanging bottle are able to simultaneously create positive and negative pressure (vacuums) without the use of mechanical pumps by simply making use of the variation in atmospheric pressure over short elevational heights of several hanging bottles in a stepped series. Pumps and hand held syringes have also been used for irrigation purposes.
The inventors have discovered that the problem of irrigating tissue is basic and that you must meet several needs of the medical situation such as:
1. The system must be sterile and maintain its sterility which means it should not be open to the air, in other words, it must be a closed system.
2. It must provide irrigating fluid at whatever controllable pressure is needed.
3. It must provide whatever flow/volume rate is needed at that chosen pressure.
4. It must provide the fluids in the total volume and at the temperature needed by the patient as decided by the surgeon or technician present.
5. The system must be reliable so that it will not fail.
Additional to these absolute must-do features, the system should also desirably include the following features:
1. Be easy to clean to medical standards.
2. Be easy to set up and use.
3. Be reasonably priced, and
4. Be extremely reliable.
It is not always possible to accomplish all of the desirable features but the absolutely required features listed under 1 through 5 above must always be accomplished.
Our study has indicated that too many of the desirable features have been provided in irrigation systems while some of the absolutely required features have not been provided. For example, many devices are made of throw-away, one-time use, plastic which is the ultimate for cleaning; yet, these items can more easily be cleaned than replaced by the hospital and a great deal of supposedly sterile devices have been contaminated at delivery which is highly undesirable for the patient. On the other hand, many industrial production procedures in use today provide precisely heated, extremely uncontaminated fluids, at exactly required volumes and pressures to closed retorts or to processing reactors; yet, there is no known system of irrigation in use in the medical field which is as accurate as these industrial systems.
B. Aspiration--(Which is the removal by suction of air or fluid from a body cavity from a region where unusual collections have accumulated or from a container.)
As has been mentioned in our U.S. Pat. No. 3,990,452 the use of aspiration to remove fragmented dissolved or particulized biotissues is extremely old dating back to the Majima regime in Japan in A.D. 600. Aspiration or the removal of fluids from body cavities by use of an aspirator or the drawing or removing by suction can readily and without additional explanation be seen to be the application of a simple vacuum technique or more preferably and precisely the use of negative pressure to a tube, hose, needle, cannula, et al. Such negative pressure (vacuum) obviously has precise and exact limitations, ultimately reaching at its maximum 14.7 lbs/in.sup.2 (1033.5 gms/cm.sup.2) or converting to a more usable standard gauge, 33.9 feet of water (29.91 inches of Hg) at 0.degree. C. and sea level.
There are many obvious methods for achieving relatively low pressure differentials or variations from the 29.9 inches of Hg standard pressure, down to the 0.1 inches of Hg required for use in medical work or in any usage of suction required for successful removal of fluids from the body cavities. Ultimately, however, since the limit of all methods are dependent from the atmospheric air pressure at sea level, they are in turn dependent upon the gravitational force; in other words gravity--applied to the air mass existing at the operating site of the aspirator--such pressure is therefore primarily a physical phenomenon of the terrestrial environment.
Generally, medical aspiration of body cavities can be accomplished with the so-called "low vacuum" range of low atmospheric negative-pressures, i.e., 14.7 lbs/in.sup.2 (1033 gm/cm.sup.2, or 10 torr) down to 1/76 th of an atmosphere, or 0.193 lbs/in.sup.2 (13.59 gm/cm.sup.2); in other words, -750 mm Hg (-29.52" of Hg). (All pressures will be indicated in mm of Hg air pressure at 0.degree. C. and sea level, and flow rates in ml/second--milliliters per second).
Since 1 torr=1 mm of absolute pressure, a negative-pressure of 10 torr, "low vacuum", would equal -750 mm Hg (-29.52" Hg) which can be readily obtained with most mechanical pumps of the piston, roller, diaphragm, vane, peristaltic types, and no vapor pumps are required.
Many types of mechanical pumps have been used for creating the negative-pressures used for evacuating body cavities, however, all of these do not have equal desirability for medical usages, as will be seen later.
C. Medication--(The act of medicating a medical substance or medicine to treat diseases by the giving of drugs; to impregnate with a medicinal substance.)
There are many widely scattered devices used for biotissue medication with the simplest, and most often used, being the standard medical syringe with a regular needle as its injector/applicator. Very little prior art exists for the simultaneous application of ultrasound and medication in the patented art.
In our invention, direct sonification is administered to the patient by way of the direct application of the tool of the invention into the tissue. In contrast, in heart/lung machines, medicine is delivered to the machine and is then carried by the circulatory system of the machine to the patient, thus, confining its spread to that single path. This allows the doctor to use very strong medicines, and even materials which are not medicines, in the machine which then carries them into the patient under the severely constrained and positive strict control of the doctor. For example, dental drilling using ultrasound sometimes has used abrasive granules of boron carbide which after application is then removed since swallowing such material is not healthy or desirable. Another example exists in closed cycle anesthesia machines.
The present invention describes a unique closed system of flow control, feedback sensing and removal, which allows new usage of simultaneous injectable medicaments.
D. Power Control--(The control of the time rate of doing work which, since we use watts, is equal to 10.sup.7 ergs/sec.)
Since in the use of ultrasound, a relatively unknown form of energy is applied to human tissues, it is very important that the total time-power, indicated in scientific units, be known. While the problem of determining the exact power going into the tissue is extremely difficult and in its early infancy, nevertheless, it is possible to accurately know the amount of power going into the ultrasonic applicator. Also, by using proportionality and substitution techniques, the time intensity exposure of the tissue to the radiation level being applied can be ascertained.
The prior art nowhere discusses the problem of measuring the true power in watts into the tissue at the application site.
In the present invention the correlation of a scientific watt, determined by a standard ampere method into a known resistance which has been developed by the inventors, allows more accurate calibrating and testing procedures for power control.
E. Duration Control--(The control and recording of the time of application of ultrasonic energy.)
The inventors use an elapsed time indicator which records in minutes and seconds the summation of the total time of application of ultrasonic energy which in turn is a measure of the total ultrasonic exposure time. Then the simple and single most important need is to accumulate the total time of application of the ultrasound as it is applied, to achieve the important intensity/dwell time factor. Thus, upon the application of three watts of ultrasound for 4 minutes--which constitutes 12 watt-minutes--we need to know if this has the same curative or traumatic effect as 6 watts of ultrasound applied for 2 minutes which also is equal to 12 watt-minutes? The inventors have also developed an operating hand piece which when used for surgery for example, can be flash autoclaved at 380.degree. F. at 50 p.s.i.--an unusual accomplishment.